1. Field of the Invention
The present invention relates to a process for the production of resin extended pigments which exhibit improved dispersiblity over the corresponding nonresin extended pigment in a variety of plastics applications.
Pigments are widely used in various types of polymeric media. The efficiency of a pigment as a color imparting substance is very dependent on the degree of pigment dispersion achieved in these media. Generally pigments are products having a very small particle size with a consequent tendency to form aggregates during their preparation. This tendency to form aggregates is particularly troublesome during the drying step used in the preparation of pigments. In order to overcome this tendency to form aggregates various methods have been used to prevent or minimize the formation of aggregates and thus enhance dispersibility of the pigment involved.
2. Prior Art
U.S. Pat. No. 2,539,429 discloses comilling a pigment and a water insoluble resin in the presence of a water miscible solvent for the resin. The solvent is then removed with water.
U.S. Pat. No. 2,544,636 discloses comilling a pigment and a resin in the presence of a solvent for the resin to produce a free flowing pigment base.
U.S. Pat. No. 2,649,382 discloses a process wherein a pigment and a soluble resin are comilled with a mixture of water and a water miscible solvent for the resin.
U.S. Pat. No. 3,705,816 discloses grinding a pigment, a cellulose ester and a water miscible organic solvent for the cellulose ester.
U.S. Pat. No. 3,806,464 discloses a process for preparing a pigment encapsulated with an acrylic interpolymer by comilling the pigment, the acrylic interpolymer and a solvent for the acrylic interpolymer. After the comilling step, the solvent is removed.
U.S. Pat. No. 3,925,096 discloses a process for producing a particulate resin-containing pigment composition in which an organic solvent soluble resin and pigment are comilled in the presence of an organic solvent.
British Pat. No. 895,751 discloses a process for forming a pigment preparation wherein a pigment is milled with a solution of a polymerization or polycondensation product followed by precipitation of the polymerization or polycondensation product.
British Pat. No. 1,431,636 discloses ball milling a pigment with a solution of a polyester-polyurethane to form a pigment paste.
Canadian Pat. No. 554,960 discloses milling a pigment and a plastic in the presence of water, a water miscible solvent for the plastic and a water immiscible solvent for the plastic.